I didn't find a SQL standard about `and chain`. IMO, whether the answer is "yes" or "no", we should update the statistics. For notify, however, I'm not sure.
Please find enclosed a new patch.
This patch includes the update of the statistics in case of commit and chain.
This patch does not notify in case of commit and chain. Notify will only be triggered should a proper commit be called. I updated the documentation to explain that behavior.
The patch has been compiled and tested successfully on the latest master branch.